It’s possible, but it would be ill advised. 1. Vari-mu (short for Variable Mu, also a Manley trademark) designs use a vacuum tube in place of a transistor, where the variable voltage input changes a tube’s bias instead of a transistor’s gain. So, they’re often smooth out harsh sounding audio. Is strange 470K for plate, did you try lower resistance? chris says: 01/27/2015 at 6:53 pm Hi. The rate at which the gain increases or decreases has a major influence on the overall quality of the compression effect. One of the first types of compressor offered was a so-called optical compressor, as made famous by compressors such as the Teletronix LA-2A. Guitarists are mostly aware of this since these kind of amps are common. Too good to be true. Your email address will not be published. But this is one of those circuits that just won't leave me alone, churning in the back of my mind, a cheap, easy, MUSICAL tube compressor. Despite the fact that this distortion only contributes 0.2% of to the amplified signal, the human ear ( subjectively ) finds it appealing. Required fields are marked *. Tube based ( or valve based ) compressors were, in early days of audio, the only choice of machine-modifying gain. This circuit uses a light source and a photocell (phototransistor) or LDR (light dependent resistor). And honestly, I think this thing probably won't sound too good. BASIC TUBE CAIN CONTROL In the better designs the tubes are Var-Mu or variable mu ( in the tubes books, also known as remote cut off). They need certain amount of time to warm up so that they can become stable. Required fields are marked *. I will like a clean sound. This voltage directly drives the gain of the tube. information and ideas about audio history, on A Simple One-Tube Compressor Circuit c.1953, The JVC 900 Digital Audio Mastering System of the early 1980s, A DIY Broadcast Limiter Project circa 1955. But a suspicion isn't a valid reason to discount something that MIGHT be good. DOWNLOAD THE COMPLETE ARTICLE:Constant Output Broadcast Amplifier. There is no much explication about this compressor circuit . I would recommend putting at least one voltage-gain stage ahead of it, and an interstate volume control as well. The AMR “System 1” 4-track cassette recorder of 1986, ADM Mixers and Consoles of the 1970s and 1980s, Effectron Digital Delays Original Catalog. In the cases of valves, this occurs at exactly twice the frequency of the amplified signal. Opto (Optical) – named accordingly. The principle on which they were working was that the level detector circuit sends the voltage to the tube. Mine sounding pretty awesome…cheers! chris says: 01/27/2015 at 6:53 pm Hi. Hi. Your email address will not be published. 6 replies on “A Simple One-Tube Compressor Circuit c.1953” alex says: 01/22/2015 at 5:50 pm would this work at the front end of guitar amp? … Save my name, email, and website in this browser for the next time I comment. The 6386 tube being the most popular part. Today Manley makes the state of the art update on this approach. While the overall unit is probably not something you’d want to ‘F’ with, the limiter component could be added to a DIY tube mic preamp (perhaps with a true-bypass switch). Before they completely warmed up, tube based audio processing devices can give you fluctuating outputs. On the most basic level, tubes amplify electricity. It’s possible, but it would be ill advised. Fairchild and Altec compressors were the early devices built on this principle. Today Manley makes the state of the art update on this approach. http://www.ovnilab.com/articles/tubecomps.shtml, Your email address will not be published. In audio, vacuum tubes lend a characteristic sound when used as an audio amplifier. I am not sure exactly how it works but it sounds awful and i don’t recommend that anyone build it, total waste of time.